String

1. The escape sequence represents one character, so only one character counts.

   let str="hello\nworld";
   console.log(str.length);
   / / 11
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2. Strings in ECMAScript are immutable; once created, their values cannot be changed. To change a string value in a variable, you must destroy the original string and then assign a new string.

   let str = "abc";
   str[0] = 'A';
   console.log(str);
   //abc
   ​
   str = "Abc";
   console.log(str);
   //Abc
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String conversion

1. Calls the toString() method of the value. Null and undefined do not have this method.

2. Use the String() transformation function

   • The toString() method is called if there is one.
   • If the value is null, “null” is returned.
   • If the value is undefined, return “undefined”.

Template literals

1. Enclose the string with backquotes above the TAB key.

2. It will keep the space inside.

3. Interpolate with ${}.

   let a = 1, b = 2;
   let str = `${a}+${b}=${a + b}`;
   console.log(str)
   / / 1 + 2 = 3
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4. All inserted values are converted to strings using toString().

   let person = {
     name: 'wn'.age: 18.toString() {
       return this.name + this.age; }}let str = `info:${person}`;
   console.log(str);
   //wn18
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5. HTML string concatenation provides great convenience.

   let person = {
     name: 'wn'.age: 18
   }
   let str = `<p><span>${person.name}</span>:<span>${person.age}</span></p>`;
   document.write(str);
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6. You can insert the value before itself.

   let str='abc';
   str=`${str}abc`;
   str=`${str}abc`;
   console.log(str);
   //abcabcabc
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Raw string

1. throughString.raw()The tag functionGets the raw string.

console.log('\u00A9');
console.log(String.raw`\u00A9`);
/ / ©
//\u00A9
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